The present invention relates generally to diagnostic systems for internal combustion engines, and more specifically to systems for diagnosing an air handling mechanism of the engine based on air handling system response analysis.
Systems for diagnosing engine components based strictly on the behavior of such components are known and have been implemented extensively in the automotive and diesel engine industries. However, with such conventional diagnostic approaches, it is difficult to diagnose some fault conditions associated with electrically actuatable control mechanisms.
For example, a control system coupled to an internal combustion engine may include a control mechanism having an actuator responsive to an actuator command to control the mechanism to a specified position, and a position sensor producing a signal indicative of a position of the mechanism relative to a reference position. Using conventional diagnostic techniques, the sensor signal is typically analyzed to determine the overall operability of the mechanism and/or to determine fault conditions associated with the sensor itself. However, fault conditions and/or failure modes may occur with respect to the actuator and/or the mechanism itself that are undetectable via analysis of the sensor signal alone. As one specific example, the signal produced by a control valve position sensor may indicate that the valve is moving and operating normally even though a failure condition exists that prevents the valve from forming a proper seal with a valve-sealing surface.
It is accordingly desirable to develop a component diagnostic strategy that provides the capability to distinguish between fault conditions and/or failure modes associated with a control mechanism, an actuator of the control mechanism and a position sensor associated with the control mechanism.
In accordance with the present invention, the response of one or more engine components, separate from and in addition to the position of a control mechanism, is included in the diagnostic analysis. By additionally considering the response of one or more engine operating components to a control mechanism command, fault conditions and/or failure modes may be distinguished as being associated with the control mechanism, the control mechanism actuator or the control mechanism position sensor.
These and other objects of the present invention will become more apparent from the following description of the preferred embodiment.